This invention relates to methods and compositions useful in the manufacture and use of ceramic and refractory compositions. More particularly this invention relates to methods and compositions for accelerating the hardening of compositions containing hardburned magnesia or deadburned magnesia, both of which are simply referred to herein as "magnesia aggregate", and a curable phenolic resin, with or without the inclusion of an ester functional hardening agent. The acceleration in hardening is accomplished by incorporating in the compositions certain compounds, such as those which supply: acetate; adipate; 1,2,4-benzenetricarboxylate (trimellitate); formate; glycolate; lactate; nitrate; succinate; sulfamate; phenolsulfonate; or toluenesulfonate anions to the composition; an acetylacetone (2,4-pentanedione); 2-nitrophenol; 4-nitrophenol; or salicylaldehyde compound; or a mixture of compounds which supply said anions or compounds.
It is often desirable to accelerate or shorten the time it takes for phenolic resins to harden a magnesia aggregate. This is particularly the case in cooler climates and at lower temperatures. Accelerators are also advantageous for reducing the strip time of molded or cast materials. The methods and compositions of this invention accomplish such acceleration in hardening.